A Simple Turn-off Schiff Base Fluorescent Sensor for Copper (II) Ion and Its Application in Water Analysis.

Xing Zhang,Ya-Li Huang,Xian-Jiong Yang,Carl Redshaw,Qi-Long Zhang,Ling-Yi Shen,Hong Xu

doi:10.3390/molecules26051233

Xing Zhang, Ya-Li Huang + Show 5 more

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https://doi.org/10.3390/molecules26051233

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Abstract

An aniline-functionalized naphthalene dialdehyde Schiff base fluorescent probe L with aggregation-induced enhanced emission (AIEE) characteristics was synthesized via a simple one-step condensation reaction and exhibited excellent sensitivity and selectivity towards copper(II) ions in aqueous media with a fluorescence “ turn-off ” phenomenon. The detection limit of the probe is 1.64 × 10−8 mol·L−1. Furthermore, according to the results of the UV-vis/fluorescence titrations, Job’s plot method and 1H-NMR titrations, a 1:2 stoichiometry was identified. The binding constant between L and Cu2+ was calculated to be Ka = 1.222 × 103. In addition, the AIEE fluorescent probe L could be applied to detection in real water samples with satisfactory recoveries in the range 99.10–102.90% in lake water and 98.49–102.37% in tap water.

Highlights

Application in Water Analysis.In recent years, fluorescent probes have been widely used in the field of rapid detection due to advantages such as ease of operation, low cost, high selectivity, and sensitivity [1,2,3,4]
The probe LL emits thethe solid state butbut the the emission decreases dradramatically in the dissolved state, so we propose that this probe may exhibit matically in the dissolved state, so we propose that this probe may exhibit aggregation-induced emission enhancement (AIEE) properproperties
We tested the time-dependent optical stability of probe L and the and the L-Cu2+ mixture, and the results showed that L and the L-Cu2+ complex were stable over a certain period of time

Summary

Introduction

Fluorescent probes have been widely used in the field of rapid detection (food, metal ion, anion, biomarker, etc.) due to advantages such as ease of operation, low cost, high selectivity, and sensitivity [1,2,3,4]. Copper is an earth abundant element which plays an important role in many domains like industrial material, [5] bactericide, and herbicide [6,7], etc. It produces toxic effects on the growth of animals and plants, and lead to risks to human health via the food chain [8,9,10]. Lack or excess of copper will cause health damage

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